VACAVILLE (CBS / AP) — As residents of a quiet Vacaville street got ready for church or a day of relaxation, an explosion shook their homes Sunday morning. Seconds later, they saw the victim of the violence — a friendly elderly neighbor who shared tomatoes from his garden — spattered with blood and with one finger nearly severed by a bomb that went off when he retrieved a newspaper from the lawn near his driveway.

“I thought something in the garage had exploded,” said Gil Guerrero, a firefighter with emergency medical training who lives across the street from the victim and was at his side moments after the bomb went off.

The force of the blast nearly took off a finger on the man’s right hand and caused other injuries to his arm and side, Guerrero and other neighbors said Monday.

Police in Vacaville would not identify the victim, who is in his 80s, and advised his family members not to release their names or discuss the case, in the event a threat to their safety remains.

The victim’s wife and his son, who asked to be identified only as “John,” got word Monday afternoon that the victim was out of surgery and recovering in serious condition at University of California Davis medical center in Sacramento.

“We don’t know any details about how he’s doing,” the son said. “Any surgery at his age is anything but routine.”

He added his father was conscious enough after the blast to ask a neighbor to notify his family and provide the son’s phone number.

“He was breathing. He had an airway,” Guerrero said, noting rescue workers arrived within minutes of the blast around 10:20 a.m. “He was saying ‘the bomb, the bomb’ so he had some idea of what had happened.”

Why and how it happened remains an open question.

Vacaville police and the federal Bureau of Alcohol, Tobacco and Firearms worked Monday to identify the bomb-maker, but remained tight-lipped about the investigation. No suspects have been named, nor has a motive been established.

The bomb apparently was inside a newspaper, but it was unclear whether the newspaper was intended for the victim. Homes in the area on Monday had copies of at least two different publications sitting on their lawns and driveways, some delivered by subscription and others delivered for free as a promotion.

The neighborhood was evacuated for hours after the blast while FBI and ATF investigators and bomb-sniffing dogs from nearby Travis Air Force Base and the California Highway Patrol searched the area for other bombs. They found none, and police said they have no reason to believe there are more; neighbors were allowed to return home starting late Sunday afternoon

By Monday, the sun had come out and neighbors talked about the shock.

The compact neighborhood of two-story houses is home to families with children, empty-nest couples, highway patrol officers and military personnel. Three doors down from the house where the bomb went off is a home that holds a daycare center on weekdays.

“Fortunately it was on a Sunday, so the kids didn’t get scared,” said Stephannie Guerrero, a parks police dispatcher married to Gil Guerrero.

Neighbors said the blast left a depression about a foot across in the lawn between the victim’s house and the one next door, and a scent of burning. Investigators dug out the blast site looking for evidence, leaving about a 3-foot-wide, water-filled crater in the yard.

Fear after the blast was a sharp contrast to pleasant memories that neighbors offered about the victim, who enjoyed riding his bicycle around the neighborhood and working in his garden.

“He brought tomatoes over one time,” neighbor John Marin said. The victim was originally from Spain, Marin added, but had been in the United States for a long time and moved to Vacaville to be close to family after he retired.

Gil Guerrero said the man kept his garage meticulously clean and would often call “You have beautiful dogs!” when the firefighter took his Rottweilers for a walk.

The circumstances of the blast, at a time when at least one newspaper is being delivered in the neighborhood for free as part of a promotion, were especially disconcerting.

Neighbors weren’t sure what newspaper was used, Marin said. “When I got over there, it looked like confetti.”

(Copyright 2011 by CBS San Francisco. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. Wire services may have contributed to this report.)